Process for rendering metal surfaces antiseptic and products therefrom



Patented Nov. 6, 1951 a s Ares PATEN OFFICE PROCESS FOR RENDERING'METAL SUR- FACES ANTISEWTIC AND PRODUCTS THEREFROM William F. Ringk, Newark, N'; J., and Stanley K. Freeman, Brooklyn, N. Y., assignors to Benzol Products Company, Newark, N. J., a corporation of New Jersey No Drawing. Application July 28, 1948,

Serial No. 41,182 Y 22 Claims. (01. 204-38) range finders, etc., to mention only a few places where such growths of micro-organisms may'occur.

It is important to arrest or inhibit such growths and under the usual conditions of use, it may be impractical or impossible to arrest such growths, particularly on inner sealed surfaces, without injury to the article or metal surface employed therein.

The principal object of the present invention accordingly is to'provide a process for rendering such surfaces antiseptic and to maintain them in such condition whether the surfaces be sealed inside the article or exposed; and to produce products having such antiseptic characteristics.

We have found in accordance with our invention that we may coat metals and alloys thereof, such as aluminum, tin, zinc and magnesium with an oxide coating and'that we may render this coating antiseptic with a substance selected from the group consisting of s-quinolinol, a salt.

thereof, or a derivative which We define as a nuclear-substituted 8-quinolinol or a'salt thereof, or a mono-, di-, or poly-azo derivative of 8- quinolinol or a salt thereof. The oxide coating and the antiseptic material may be deposited simultaneously or in separate operations in accordance with our invention and such coatings may be dyed by the application of colors thereto capable of coloring the coating; these colors being applied simultaneously with the production of the antiseptic coating or at any time during the process. our invention products which have the desired characteristics of protection of the metal against the usual oxidation and other actions occurring Thus, we may produce in accordance with in use but which are also resistant to the growth of micro-organisms, while at the same-time the metals are provided with ornamental color' effects in designs'or otherwise; the result being that we are able to produce a permanent antiseptic coating which may be colored as desired.

The invention accordingly comprises the novel products'as Well as the novel processes and steps of processes according to which such products are manufactured, the specific embodiments of which are described hereinafter by way of example and in accordance with which we now prefer topractice the invention.

We have iound'in accordance with our invention that oxide coated aluminum, magnesium, tin, zinc and their alloys may be treated with 8- quinolinol or its salts, as stated above, and such salts may be B-quinolinol sulfate, hydrochloride, phosphate, benzoate, citrate, acetate, tartrate, salicylate, etc. As also stated, we may employ derivatives, i. e., but without limitation, nuclearsubstituted substances which may be halogenated nuclear-substituted compounds or nitro or nitroso nuclear-substituted compounds; or a mono-, di-, or poly-azo derivative of 8-quinolinol or a salt thereof. 7

The process may be carried out as indicated by either immersing the oxidized metal in a solution of said S-quinolinol or derivatives as defined above, or one of the salts thereof maintained at.

any temperature between 32 F. and 212 F. and within a pH range of 0 to 14. Instead of this two step treatment, however, the oxidation of the metal and application of the 8-'quinolinol, or a derivative, may occur in one step. In carrying out the production of an oxide coating on aluminum anodically, either an acid, neutral, or an alkaline bath may be employed, although the acid bath is the preferred method. In carrying out the production of an anodic oxide coating on the remaining metals, namely, tin, zinc and magnesium, an alkaline bath is employed. In carrying out the one-step process mentioned above, accordingly, S-quinolinol or its derivatives or salts thereofmay be used in the alkaline process with tin, zinc and. magnesium. It is, of course, less economical ordinarily touse the salts with the alkalinefprocessand-the base is preferred.

It will be noted'th-at'no example is'given below for the anodic treatment of aluminum in the one-step operation; that is, where the anowith the application of the antiseptic material,

- 3 as we have found that the formation of the complex does not occur satisfactorily under the conditions necessary for depositing the anodized coating in acid solution.

As a result of the process. whether it be conducted in successive steps or simultaneously. a uniformly deposited coating results which is the metal complex of B-quinolinol or other compound used and is permanently affixed to the metal accordingly.

Photomicrographs of the coating formed on the metal surface and of the coating stripped from the metal surface shows the coating to be the metal complex of B-quinolinol or other compound used. In addition, analysis of the stripped yellow coating bears out this statement, i. e., stripping an anodized film of aluminum treated with a solution of 8-quinolinol, with hot anhy drous methanol, yielded the following analysis:"

Per cent Aluminum-8-quinolinolate 99.14 Aluminum oxide 0.8

We believe that the reactions which occur in forming the complexes mentioned may be shown as given below. We are unable to state unequivocally that such reactions do occur, but we do know that a complex is formed and that it has antiseptic properties which persist for long periods. The reactions mentioned are as follows:

Reaction between 8 -quinolino1 and its salts with the oxidized metal surfaces- .uzo,+ 2x1 +smo 0 N I a nAh0;+6 HA 2 A] +anm0+srm where A is sulfate, hydrochloride, phosphate, tartrate, citrate, benzoate, etc., and n is 1, 2, or 3.

According to R. Kerr (J. Soc. Chem. Ind. 57, 405-10, 1938), the greyish-green film formed on tin when anodized in sodium hydroxide solutions has the following analysis: SnOz, 80.9%, SnO 9.3%, H20 9.8%, which corresponds to hydrated stannic oxide contaminated with stannous oxide. It is therefore probable that Equation 4B represents the major part of the reaction and Equation 4A represents a small portion of the over-all reaction.

Equations for the salts of 8-quinolinol with Mg, Zn and Sn can be formulated like Equation 2. Equations for the derivatives of 8-quinolinol with Al, Mg. Zn and Sn can be written similar to those with 8-quinolinol itself.

By the addition of a suitable organic dye, of the type generally used in dyeing these oxide coated metals and their alloys, to a solution of 8- quinolinol, its derivatives or salts thereof, colored antiseptic coatings may be obtained on aluminum and magnesium and their alloys. Colored antiseptic coatings may also be obtained by dyeing aluminum or magnesium metals and their alloys whose surfaces had been previously oxidized and treated with a solution of B-quinolinol or its derivatives or salts thereof. Still another method consists in dyeing the oxidized metal and then treating with a solution of B-quinolinol or one of its salts or derivatives or salts thereof.

Colored antiseptic coatings can also be obtained on aluminum and magnesium metals and their alloys by the use of inorganic coloring materials, 1. e., precipitating ferric oxide in an oxidized coating of these metals or alloys and then treating with B-quinolinol or one of its salts. Also, by treating oxidized aluminum or magnesium and their alloys with a solution containing a suitable iron salt and an excess of B-quinolinol or one of its salts, colored antiseptic coatings result.

The colored antiseptic coatings are characterized by a superior permanence, superior resistance to bleeding and color change on exposure to salt solutions, and, in some instances, superior fastness to light. For this and other purposes, a metal tube or other article may be coated on both its exterior and interior, for example, and then the exterior may have applied thereto a dyestuff in design or as an all-over effect.

In this connection, the tinctorial strength of certain dyes is greatly increased when 8-' quinolinol or one of its salts is used in conjunction with the dye when coloring aluminum and its alloys previously anodized in a chromic acid solution.

In practicing our invention, as we now prefer to practice it, the metals and metal alloys which are to be treated are first provided with an oxide coating of certain characteristics. The term oxide coating does not include the very thin film of metallic oxide which is naturally formed upon the metals and their alloys resulting by the action of air upon their surfaces. It is necessary that the coating be dense, adherent, hard and absorbent in nature so that it does not separate from the metal surface and has the porosity to readily combine with B-quinolinol or its salts and derivatives or salts thereof and organic dyes and absorb metallic coloring matter. The thickness of the oxide film produced is not a controlling factor.

The term oxide coating, as used herein and in the appended claims, is a well known designation of the art which describes a layer of oxide artificially produced on the surfaces by treatment on the metal surfaces with acids such as sulfuric, nitric, chromic, picric, etc., or alkalies such as sodium hydroxide, and sodium carbonate, or the; alkali sulfates such as sodium sulfate, or

salts such as ammonium oxalate, potassium chromatefsodium stannate, etc., all with "r without the addition of other substances and some with and without the use of externally-applied electrical energy.

The manner in detail of producing oxide coatings on aluminum, magnesium, zinc and tin and their alloys having the above described characteristics is well known and described in the art, and consequently only preferred solutions and methods will be specifically described.

1 In accordance with our method, as we now prefer it, where the oxide coatin and antiseptic material are deposited in separate operations, the solutions of S-quinolinol or its salts can be effectively used in hydrogen ion concentrations varying from pH 1 to 13 for aluminum, pH 0 to 14 for magnesium, pH 3 to 14' for zinc, and pH 3' to 11 for tin. A pH range of 4.5 to 9 in each instance is preferred. For s-quinolinol derivatives and salts thereof, a pH range of 7 to 14 may be employed, or, preferably, a pH range of 9 to 12.

.Very dilute solutions and/or saturated solutions of the antiseptic materials may be efi'ectively employed in the process; concentration ranges most satisfactory for general purposes lie between 0.1% and 0.5

Solutions of the above concentrations may be used at temperatures ranging from 32 F. to the boiling point. The best results are obtained when the solutions are used at temperatures ranging from 120 to 140 F.

The time of immersion of the above-mentioned surface oxidized metals in solutions of the above concentrations and temperatures may range from 1 to 30 minutes. The best results are obtained when the immersion time lies between 10 and minutes.

Where the oxide coating and antiseptic material are deposited simultaneously in a single operation, the 8-quinolinol, its derivatives and their salts may be used in solutions of the concentration employed for the two-step operation as given three paragraphs above. Solutions of these concentrations may be used at temperatures between 32 F. and the boiling point. The best results are obtained'when the temperature is restricted between 120 and 150 F. The derivatives can be effectively used in solutions of pH ranging between 7 and 14, and a pH range of 9 to 12 is preferred. The time of immersion of the abovementioned surface oxidized metals in solutions of the above concentrations and temperatures may range from 1 to minutes; optimum results are obtained when the immersion time lies between 10 and 20 minutes.

For the single step operation, magnesium, zinc,

and tin metals and alloys may be oxidized in the presence of 8-quinolinol and its derivatives. The oxidation may be carried out in solutions of alkali metal hydroxides of concentration varying between 0.1% and 30% and temperatures ranging between 75 F. and 200 F. The concentration The num, magnesium, zinc or tin article in the solu tion described above embodying two operations consists in immersing the article in the solution. Suitable examples of commercial procedures of producing antiseptic coatings on a1uminum, mag nesium, zinc and tin articles by treatin the surface oxidized metals and alloys with 8-quinolinol or one of its salts or derivatives or salts thereof,

including the one and two step operations are given herein below. In addition, suitable examples are given as to the methods of forming colored antiseptic coatings on oxide coated aluminum and magnesium articles. These examples are merely typical of the general procedure employed in producing antiseptic coated aluminum, magnesium, zinc and tin articles in accordance with the invention, and it is to be understood that the conditions employed may be varied widely as described hereinabove to obtain the characteristics desired in the product. Accordingly, these examples are illustrative of the invention and the invention is not to be considered as restricted thereto except as indicated in the appended claims.

The antiseptic action of thecoated articles described below was tested by the agar plate method and/or beef broth method in accordance with the procedure outlined in the United States Food and Drug Administration Circular No. 198.

Examples 1. An aluminum article is anodically coated in a 15% aqueous sulfuric acid solution with a current density of 15 amperes per square foot for 30 minutes at F. The article is washed in water at room temperature and then immersed in a 0.3 to 0.4 per cent aqueous solution of 8-quinolinol benzoate. for 10 minutes at a temperature of F., then washed for about one minute, buifed and dried.

A one-half inch square strip of the material, when tested against Staphylococcus aareas by the agar plate, method, exhibited a 20 mm. clear, evenly diffused zone of. inhibition, measured from one edge of the aluminum strip to the position of noticeable germ growth.

, 2. An aluminum article is anodically coated in a 6% aqueous chromic acid solution with a potential of 8 volts for 30 minutes at 110 F. The article is washed in water and immersed in a solution adjusted to a pH value between 5 and 6, containing 0.2 to 0.3 per cent aqueous solution of 8-quinolinol benzoate and 0.2 per cent Aluminum Orange 3A (Sandoz) for 20 minutes at a temperature of F., then Washed, buffed and dried. The resulting color is approximately ten times stronger than that obtained by coloring the article with the dye alone under the same conditions.

A one-halfinch square strip of the material, when tested against Staphylococcus aareas by the agarplate method, exhibiting a 10 mm. clear, evenly difiused zone of inhibition.

3. An aluminum article coated as described in Example 1 is washed and immersed in a 0.1 per cent aqueous solution of 3quinolinol for 10 mined as above in this Example 3 was'immersed'in 7 V a 3 per c'entaqueous solution of sodium chloride. Another strip treated as described above in this Example 3, except that the 8-quinolinol treatment was omitted, was also immersed in a 3 per cent aqueous solution of sodium chloride. The solutions were compared after 24 hours. The solution containing the article coated with dye and 8-quinolinol showed practically no color while the solution containing the article treated with dye alone was appreciably colored, thus indicating that the dyed and B-quinolinol treated strip was more resistant to the action of salt solution.

4.An aluminum article coated as described in Example 1 is washed and immersed in an aqueous solution containing 0.2 per cent 8-quinolinol benzoate and 0.2 per cent Aluminum Yellow 23 (Sandoz) for 10 minutes at a temperature of 125 F., then washed, buffed and dried A one-half inch square strip of the material, when tested against Staphylococcus aureus by the agar plate method, exhibited an 11 mm. zone of inhibition which was Very clear and evenly diffused.

Another strip of alumium anodized and treated as in this example was subjected to the salt water test as described under Example 3. The solution containing the dye and 8-quinolinol benzoate treated strip was practically colorless, while the solution containing the article treated with dye alone was appreciably colored, thus indicating that the former article was more resistant to the action of salt water. In addition, there was no observable change in shade or strength of the aluminum article treated with dye and B-quinolinol benzoate after the salt water test, whereas the article treated with dye alone was appreciably weaker in color.

5. An aluminum article coated as described in Example 1 is treated as described in Example 4, substituting Aluminum Green AE (Sandoz) for Aluminum Yellow 23 (Sandoz).

A one-half inch square strip of the material, when tested against Staphylococcus aureus as described in Example 4, exhibited a 13 mm. zone, very clear and evenly diffused, of inhibition.

Another strip of the anodized and treated aluminum as described in this example was compared by salt test with a strip of anodized aluminum article treated only with dye as described in Example 4. Although there was only a slight difference in bleeding (in favor of the dye-8- qninolinol treated article) there was an appreciable shade change in the article simply dyed, while there was little or no change in the shade of the dye-E-quinolinol treated aluminum article.

6. An aluminum article coated as described in Example 1 is washed and immersed in a 0.2 per cent solution of Aluminum Red S (Sandoz) for 10 minutes at a temperature of 125 F., then washed and immersed in a 0.1 to 0.2 per cent aqueous solution of 8-quinolinol tartrate for '10 minutes at a temperature of 125 F., then washed, buffed and dried.

A one-half inch square strip of the colored article exhibited an 8 mm. clear, evenly difiused zone of inhibition and a '7 mm. zone of partial inhibition when tested as described in Example 1.

7. A one-inch by six-inch collapsible aluminum tube is coated on the inner side as well as on the outside as described in Example 1, is washed and immersed in a 0.1 to 0.2 per cent aqueous solution of 8-quinolinol benzoate for 15 minutes at Y broth solution and seeded with Staphylococcus aureus. At the end of 24 hours incubation period at 375 C., a clear, germ free solution was observed. When a portion of this solution was subcultured in a sterile lactose beef broth solution, no growth of Staphylococcus aureus resulted at the end of 24 hours incubation time which indicates that the coating is bactericidal in its action.

8. An aluminum article anodically coated as described in Example 1 is washed and immersed in a 10 per cent aqueous solution of ferric oxalate to which 1 to 3 mols of potassium oxalatehasbeen added for every mol of ferric oxalate. The article is immersed for a period of 10 minutes at a temperature of F., washed, and then immersed in a 0.1 to 0.2 per cent aqueous solution of 8-quinolinol for a period of 10 minutes at a temperature of 125 F. The light brown colored article is washed and dried.

A one-half inch strip of the coated article, when tested against Staphylococcus aureus by the agar plate method, exhibited a 7 mm. clear, evenly diifused zone of inhibition.

The coated article as described above was placed in a Fadeometer along with an article treated as described above, except that it was not immersed in the 8-quinolino1 solution. At the end of 24 hours exposure, it was observed that the article treated with 8-quinolinol faded to a lesser degree than the article not subjected to the 8-quinolinol treatment.

9. An aluminum article is immersed for 20 minutes in a 5 per cent aqueous solution of sodium hydroxide, washed in water and then washed quickly in very dilute nitric acid. The article is then anodically treated as described in Example 1, washed and immersed in a 0.4 per cent solution of Aluminum Black BK (Sandoz) at 125 F. for 10 minutes. The coated material is then immersed in a 0.1 to 0.2 per cent aqueous solution of 8-quinolinol benzoate for 10 minutes at a temperature of 125 F., washed, buffed and dried.

A one-half inch strip of the dull black coated article was tested against Staphylococcus aureus using the agar plate method and exhibited a 6 mm. clear. evenly diffused zone of inhibition.

10. An aluminum article, coated as described in Example 1, is washed and immersed in a 0.2 to 0.3 per cent aqueous solution of 5-chloro 8-quinolinol adjusted to pH 11 with an alkali for 10 minutes. at a temperature of F. washed, buffed and dried.

A one-half inch by three-inch long strip was subjected to the beef broth tests as described under Example 6. No turbidity was observed after'incubating for 24 hours, and upon subculturing on an agar plate seeded with Staphylococcus aureus, a few colonies of the germ was observed, indicating that the coating was bacteriosta-tic in its action.

11. An aluminum article coated as described in Example 1 is washed and immersed in a 0.2 to 0.3 per cent aqueous solution of 5-nitroso B-quinolinol adjusted to pH 11 with an alkali for 10 minutes'at a temperature of 140 F., washed, bufied and dried.

A one-half inch strip of the yellow colored article was tested against Staphylococcus aureus using the agar plate method and exhibited a 2 mm. clear, evenly diffused zone of inhibition.

12. An aluminum article coated as described in Example 1 is'washed and immersed in a 0.2 to 0.3 per cent aqueous solution of 5-nitro 8- ,quinolinol adjusted to p11 11 with an alkali tor '9 10 minutes at a temperature of 140 washed, buffed and dried.

A one-half inch strip of theyellow colored article was tested against Staphylococcus aureus using the agar plate method and exhibited a clear, evenly diffused zone of inhibition of 2mm.

13. An aluminum article coated as described in Example 1 is washed and immersed in a 0.2 to 0.3 per cent aqueous solution of 5-chloro 7- iodo 8-quinolinol adjusted to a, pH between 10 and 12 with an alkali for 10 minutes at a, temperature of 140 F., washed, buffed and dried.

A one-half inch strip of the yellow coated material was tested against Staphylococcus aureus using the agar plate method and exhibited .a 1 mm. zone of inhibition.

14. An aluminum article coated as described in Example 1 is washed and immersed in a 0.2 to 0.3 per cent aqueous solution of.5;7-dibromo 8-quinolinol as described in Example 13, washed, buffed and dried.

A one-half inch strip of the yellowish-"green article exhibited a 1 mm. zone of inhibition when tested against Staphylococcus aureus using the agar plate method.

15. An aluminum article coated as described in Example 1 is washed and immersed in a 0.1 to 0.2 per cent aqueous solution of p-acetylaminophenyl 5-azo S-quinolinol as described in Example 13, washed, buffed and dried.

A one-half inch strip-of the'light brown (:01- ored article exhibited a 1 mm. zone of inhibition when tested against Staphylococcus aureus using the agar plate method.

16. An aluminum article coated as described in Example 1 is washed and immersed in a 0.1 to 0.2 per cent aqueous solution of 1,4-phenylbis-(5-azo 8-quinolinol) as described in Example 13, washed, buffed and dried.

A one-half inch square strip of the-brownish red article exhibited a 1 mm. zone of inhibition when tested against Staphylococcus aureus employing the agar plate method.

17. A magnesium article is anodically coated in a 25 per cent aqueous sodium hydroxide solution containing '7 per cent ethylene glycol with a current density of amperes per square foot for 20 minutes at 170 F. The article is washed in water and immersed in a 0.1 to 0.2 per cent aqueous solution of 8-quinolinol benzoate .for .10 minutes at a temperature of 125 F., then washed, buffed and dried.

A clear, very well diffused zone of inhibition of 8 mm. was obtained when a one-half inch square strip of the coated article was tested against Staphylococcus aureus employing the agar plate method. The beef broth test as described under Example 7 showed the material to be bactericidal in action.

18. A magnesium article is anodically coated as described in Example 17, washed and immersed in an aqueous solution of 0.1 to 0.2 per cent 8-quinolinol benzoate and. 0.1 per cent Aluminum Green AE (Sandoz) for 10 minutes at a temperature of 125 F., washed, buffed and dried.

When tested against Staphylococcus aureus as described in Example 1, an 8 mm. clear, evenly diffused zone of inhibition was obtained.

A magnesium article treated as described above and one also treated as described above except that 8-quinolinol benzoate was omitted, were placed in a fadeometer to subject the articles to simulated sunlight for 24 hours. The light :10 ,fastnessof the formerarticle was. superior'to latter one.

When immersed in a 3 percent aqueous sodium chloride solution for 24 hours, a magnesium article treated as described above showedless change in shade when compared to an article the coated as described above, but not treated with were not subjected tothis treatment. I l 20 20. A magnesium article is anodically'coated as described in Examplel"? and washed and treated as described in-Example 6.

Tests against Staphylococcus aureus yielded-a 6 mm. clear, well diffused zone of inhibition.

When exposed to light tests as described in Example 18, the article treated with B-quinolinol tartrate was superior to those not-subjected to this treatment.

21..A magnesium article is anodically coated as described in Example 17 and washed and treated as described in Example 8.

When tested against Staphylococcus aureus, a 6 mm. clear, well diifused zone of inhibition was obtained. 1

When exposed to light-and salt water tests as described in Example 18, the article treated'with 8-quinolinol was superior to thosenot subjected to this treatment. I

At the end of hours, the sample immersed in ferric oxalate (Example 8) and then treated with 8-quinolin01 showed practically no fading, whilethe sample untreated with S-quinolinol was appreciably faded.

22. A magnesium article is immersed in an aqueous solution containing 0.5 to 1.0 per cent sodium hydroxide and 0.2 to 0.3 .per cent 8- quinolinol with a current density of 20 amperes per square foot for 20 minutesat 140 F., washed,

buiTed and dried.

A 10 mm. clear, evenly diffused zone of inhibition was observed whentested against'Staphylococcus aureus by the agar plate method.

When subjected to the beef broth test as described under Example 7, the coated article proved to be bactericidal in nature.

23. A tin or tin-coated article is anodically coated in an aqueous 0.1 N solution of sodium hydroxide with a current density of 15 amperes per square foot for 20 minutes at 75 F.,-washed and dried. The article is then immersed lina 0.1 to 0.2 per cent aqueous solution of fi-quinolinol benzoate for 10'minutes at .F., washed, bufied and dried.

When tested against Staphylococcus aureus by theagar plate method, an 8 mm. clear, evenly, diffused zone of inhibition was observed.

24. A tinor tin-coated article is immersed in an aqueous solution containing 0.5 per cent sodium hydroxide and 0.2 to 0.3 per cent S-quinolinol with a current density of '15 amperes per square foot for 20 minutes at F., and the article allowed to remain in the solution for 5 minutes after the current had been shut off. After washing, bufiing and drying, a one-half inch square piece of the article, when subjected ass sts Staphylococcus aureus tests as described in Example 1, exhibited a 9 mm. clear, evenly I diffused zone of inhibition. In addition, the material proved to be bactericidal when tested with aStaphylococcus aureus innoculated beef broth solution as described in Example '7.

25. A tin or tin-coated article is anodically coated in a 2 per cent picric acid aqueous solution at a current density of 15 amperes per square foot for 30 minutes at 75 R, washed and immersed in a 0.1 percent aqueous solution of 8- sodium chloride when compared to an article merely anodized as described above. a

26. A zinc or zinc-coated article is anodically coated in a 25% aqueous sodium hydroxide solution with a current density of 60 amperesper square foot for 1 minute at a temperature-oi 75 F. and washed. It is immersed in a 0.1 to 0.2 per cent aqueous solution of Ei-quinolinol b enzoate for minutes at 125 F., washed," bu'fi'ed anddried Q When tested against Staphylococcus aureu's, an 8 mm. evenly diffusedzoneof inhibition was observed. 1 '7 Q The coating obtained as described above was superior to" that obtained by simply anodizing the zinc article, when tested in a 3 per cent aqueous sodium chloride'solution.

27; A zinc or zinc coated article is immersed in a 1 per cent aqueous solution of sodium hydroxidecontaining 0.2 to 0.3 per cent of 8- quinolinol with a current density of amperes per square foot for one minute at 140 F.', washed, buffedan'd dried. I

When'tested against Staphylococcus aureus by the agar plate method, an 8 mm. evenly diffused zone of inhibition was observed.

When tested bythie beef broth scribed in Example 7-, the coated to be bactericidal in nature.

The coatedarticle as described above showed superior resistance to 3 per cent aqueous sodium method as, dearticle proved chloride solution when compared with a zinc article' anodized and not treated with B-quinolinol.

2B. A zinc or zinc-coated article is immersed in a 25 per cent aqueous solution of Yellow Anozinc Compound 50, believed to be a basic zinc chromate, at room temperature. A current of 25 amperes per'square 'foot for 3 min'utes is passed through the system; the article is washed and dried, and sealed in a boiling 2 per cent solution of sodium carbonate. .The article is then 1111- 'mersed in a 0.1 to 0.2 percent aqueous solution of fl-quinolinol at 175 F. for'10 minutes, washed, bufied and dried.

When tested against Staphylococcus'aureus by the agar plate method, a 4 mm. clear, evenly diffused zone of inhibition was observed.

29. A magnesium article is anodically coated as described in Example 17, washed and treated in a 0.2 to 0.3 per cent aqueous solution of 5-nitro 8-quinolinol adjusted to a pH of 10 to 12 with an alkali. Thearticle was washed, bufiedand dried and one-half inch square strip, when sub- Jected to the action of Staphylococcus aureus employing the agar plate method, exhibited a 6 mm.'clear, evenly difiusel zone of inhibition. with.

12 slight leaching of the bright yellow colored coat ing into the zone. 1

30. A zinc or zinc-coated article is treated with Yellow Anozinc Compound 50 as described in Example 28, sealed in 2 per cent boiling aqueous sodium carbonate solution and washed. The article is then immersed in a 0.2 to 0.3 per cent aqueous solution of 5-chloro B-quinolinol adjusted to a pH of 10 to 12 with an alkali at 140 F. for 10 minutes, washed and dried.

When tested against Staphylococcus aureus by the agar plate method, a 3 mm. clear, evenly diffused zone of inhibition was observed.

31. A zinc or zinc-coated article is coated and treated as described in Example 30, substituting 5-nitro 8-quinolinol for 5-chloro S-quinolinol.

When tested against Staphylococcus aureus employing the'agar plate method, a 3 mm. clear, evenly diffused zone of inhibition was observed.

32. A tin or tin-coated article is immersed in a 70 per cent nitric acid solution for from 10 to 15 seconds, washed, and then immersed in a 0.1 to 0.2 per cent aqueous B-quinolinol solution for 10 minutes at F., washed, buffed and dried.

A one-half inch square strip of the yellowcoated article was tested against Staphylococcus aureus using the agar plate method and exhibited at 15 mm. clear, evenly diffused'zone of inhibi tion.

It will be noted that the above examples employ water as the medium or dissolving the 8- quinolinol and similar substances. Instead of water, alcohols such as methanol, ethanol, propanols, butanols, and various other liquid alcohols, as well as other organic'solvents, either alone or mixed with water may be employed as solvents.

The metals and alloys thus rendered antiseptic through oxide coatings containing B-quinolinol metal complexes and other compounds herein mentioned may be employed among other purposes for: Collapsible tubes for use in the pharmaceutical, cosmetic, food and other industries; optical instruments, 1. e., telescopes, binoculars, cameras, range finders, etc. are protected against the action of fungi and bacteria by treating the anodized dull black barrels, casings, etc. with 8- quinolinol, one of its salts or derivatives; closures and liners for glass bottles containing pharmaceutical and cosmetics products, specifically,

aluminum seals, such as used on multiple dose containers for serums, vaccines, antibiotics and other medicinal preparations, are protected and otherwise benefited when treated as described above; structural metals used in the brewing, dairy and pharmaceutical industries, i. e., corrugated sheets, sidings, T, I, and channel beams, storage tanks, etc. are protected and otherwise benefited when treated as described above.

In the appended claims where reference is made to the metals, aluminum, tin, magnesium or zinc, such reference is intended to cover the known alloys of such metals which have the same or equivalent characteristics for use in the processes and products of our invention.

The expression used in the appended claims, substance capable of coloring, the oxide coating is intended to designate organic dyestufis as well as inorganic coloring materials hereinabove referred to, but without limitation to the specific substances disclosed in the specification unless so indicated in said claims.

What we claim'is:

1. A process for coating metal which comprises, applying t a metal selected from the group consisting of aluminum, magnesium, tin, and zinc, an oxide coating of one of said metals corresponding to the metal treated and a quinolinol substance selected from the group consisting of B-quinolinol, a salt thereof, a nuclear substituted 8-quinolinol, a salt thereof, an azo 8- quinolinol derivative, and a salt thereof, and forming a compound between said oxide and said quinolinol substance thereby forming a bond between said metal, said oxide and said'quinolinol substance.

2. A process for coating metal which comprises, oxidizing a metal surface selected from the group consisting of aluminum, magnesium, tin and zinc, to form an oxide coating, thereafter rendering the coating antiseptic by combining with it a quinolinol substance selected from the group consisting of S-quinolinol, a salt thereof, a nuclear-substituted 8-quinolinol, a salt thereof, an azo 8-quino1inol derivative, and a salt thereof, and forming a compound between said oxide and said quinolinol substance thereby forming a bond between said metal, said oxide and said quinolinol substance.

3. A process for coating metal which comprises, anodizing a metal surface selected from the group consisting of aluminum, magnesium, tin and zinc to form a coating of the corresponding oxide, immersing the coated material in a solution of 0.1 to 0.5% of a quinolinol substance selected from the group consisting of B-quinolinol, a salt thereof, a nuclear-substituted 8- quinolinol, a salt thereof, an azo S-quinolinol derivative, and a salt thereof, in a pH range of about pH 4.5 to about pH 12 at a temperature within the range from about 120-l40 C. for a period of about to minutes, and forming a compound between said oxide and said quinolinol substance thereby forming a bond between said metal, said oxide and said quinolinol substance.

4. A process for coating metal which comprises, anodizing a metal surface selected from the group consisting of magnesium, tin and zinc in the presence of a quinolinol substance selected from the group consisting of B-quinolinol, a salt thereof, a nuclear-substituted S-quinolinol, a salt thereof, an azo 8-quinolinol derivative, and a salt thereof, and forming a coating of the oxide corresponding to the metal combined with said substance, thereby forming a bond between said metal, said oxide and said quinolinol substance.

5. A process for coating metal which comprises, anodizing a metal surface selected from the group consisting of magnesium, tin and zinc in the presence of.a quinolinol substance selected from the group consisting of S-quinolinol, a salt thereof, a nuclear-substituted S-quinolinol, a salt thereof, an azo 8-quinolinol derivative, and a salt thereof, said anodizing Occurring in an alkaline solution, and forming a film consisting of metal oxide and metal complex of said substance, thereby forming a bond between said metal, said oxide and said quinolinol substance.

6. A process in accordance with claim 1 in which the oxide coating is formed by anodizing and S-quinolinol is used.

'7. A process in accordance with claim 3 in which the oxide coating is formed by anodizing and is treated with S-quinolinol benzoate.

8. A process in accordance with claim 3 in which aluminum is treated with S-quinolinol.

9. A process in accordance with claim 3 in which magnesium is treated with B-quinolinol sulfate.

10. A process according to claim 4 in which which zinc is treated in the presence of S-qui'nolinol.

13. A process for coating metal which comprises, applying to a metal selcted from the group consisting of aluminum, magnesium, tin, and zinc, an oxide coating combined with a substance capable of coloring said oxide and with a quinolinol substance selected from the group consisting of 8-quinolinol, a compound containing a nuclear-substituted 8-quinolinol, an azo 8- quinolinol derivative, and a salt thereof, and forming a compound between said oxide and said quinolinol substance thereby forming a bond between said metal, said oxide and said quinolinol substance.

14. A process for coating metal which comprises, anodizing a metal selected from the group consisting of aluminum, magnesium, tin and zinc to form a coating of the corresponding oxide, immersing the coated material in a solution of 0.1 to 0.5% of a quinolinol substance selected from the group consisting of ii -quinolinol, a salt thereof, a nuclear-substituted 8-quinolinol, a salt thereof, an azo 8-quinolinol derivative, and a salt thereof, in a pH range of about 4.5 to about pH 12 at a temperature within the range from about -140 C. for a period of about 10 to 20 minutes, together with a dye capable of dyeing said oxide coating, and forming a compound between said oxide and said quinolinol substance thereby forming a bond between said metal, said oxide and said quinolinol substance.

15. As a new article, a coated metal, said metal being selected from the group consisting of aluminum, magnesium, tin, and zinc having a coating of a compound of the oxide of the metal with a quinolinol substance selected from the group consisting of s-quinolinol, a salt thereof, a nuclear-substituted s-quinolinol, a salt thereof, an azo B-quinolinol derivative, and a salt thereof.

16. As a new article, a coated metal. said metal being selected from the group consisting of aluminum, magnesium, tin, and zinc coated with a compound of an anodized oxide of the metal with a quinolinol substance selected from the group consisting of s-quinolinol, a salt thereof, a nuclear-substituted 8-quinolinol; a salt thereof, an azo B-quinolinol derivative, and a salt thereof.

17. As a new article, a coated metal, said metal being selected from the group consisting of aluminum, magnesium, tin, and zinc coated with a compound of an anodized oxide of the metal with a quinolinol substance, said coating being colored by a coloring substance, said quinolinol substance being selected from the group consisting of S-quinolinol, a salt thereof, a nuclearsubstituted 8-quinolinol, a salt thereof, an azo 8- quinolinol derivative, and a salt thereof.

18. As a new article, a coated metal, said metal being selected from the group consisting of aluminum, magnesium, tin, and zinc coated with a compound of an anodized oxide of the metal with S-quinolinol.

19. As a new article, aluminum having a coating of a compound of anodized aluminum oxide with 8-quinolinol.

20. As a new article, magnesium having a coating'of a compound of anodized magnesium oxide with 8-quino1ino1.

21. As a new article, tin having a coating of a compound of anodized tin oxide with 8-quinolinol.

22. As a new article, zinc having a coating of a compound of anodized zinc oxide with 8-quinolinol.

WILLIAM F. RINGK. STANLEY K. FREEMAN.

REFERENCES CITED The following references are of record in the file of this patent:

OTHER REFERENCES Journal of Society of Chemical Industry, 1940 (59), pages 34, 35, 38, 39.

Certificate of Correction Patent N 0. 2,574,225

WILLIAM F. RINGK ET AL.

It is hereby certified that error appears in the printed specification of the above numbered patent requirmg correction as follows:

Column 3, lines 34, 46, 53, 60, 63, 68 and 71, in the rence, for the letter Z read 1V; column 6, line 61, for

zted column 7 line 53, for qninolinol read guz'nolz'nol;

November 6, 1951 THOMAS F. MURPHY, 

1. A PROCESS FOR COATING METAL WHICH COMPRISES, APPLYING TO A METAL SELECTED FROM THE GROUP CONSISTING OF ALUMINUM, MAGNESIUM, TIN, AND ZINC, AND OXIDE COATING OF ONE OF SAID METALS CORRESPONDING TO THE METAL TREATED AND A QUINOLINOL SUBSTANCE SELECTED FROM THE GROUP CONSISTING OF 8-QUINOLINOL, A SALT THEREOF, A NUCLEARSUSSTITUTED 8-QUINOLINOL, A SALT THEREOF, AN AZO 8QUINOLINOL DERIVATIVE, AND A SALT THEREOF, AND FORMING A COMPOUND BETWEEN SAID OXIDE AND SAID QUINOLINOL SUBSTANCE THEREBY FORMING A BOND BETWEEN SAID METAL, SAID OXIDE AND SAID QUINOLINOL SUBSTANCE. 